1. Field of the Invention
The present invention relates to a method of automatically adjusting a CRT color monitor screen and to a CRT color monitor. More particularly, the present invention relates to a method of automatically adjusting position and size on a CRT color monitor screen in accordance with an unknown input video signal and to a CRT color monitor employing the method.
2. Description of the Prior Art
Such conventional methods of automatically adjusting a CRT color monitor screen are well known and two techniques of them are disclosed in Japanese Patent Laid-open Publications No. HEI5-27689/1993 and No. HEI8-194444/1996.
The technique disclosed in HEI5-27689/1993 has a timer built in a microcomputer assigned for measuring a beginning of a picture signal part of a video signal to perform an automatic screen position adjusting operation.
The technique disclosed in HEI8-194444/1996 permits a measuring circuit with a counter for counting clocks to measure the beginning and an end of the picture signal part of the video signal and uses a result of the measurement in a microcomputer for automatic adjusting of position and size on the screen.
However, in the technique disclosed in HEI5-27689/1993, the timer built in the microcomputer provided for measuring the beginning of the picture signal part is low in the resolution of time. Assuming that the horizontal frequency is 100 kHz, the accuracy of measurement will be declined thus providing a lower accuracy in adjusting the horizontal position.
In the technique disclosed in HEI8-194444/1996, the measuring circuit is operable at a high speed and provides a high accuracy of measurement when the horizontal frequency is 100 kHz or so hence ensuring a higher accuracy in adjusting the horizontal position. The use of the high speed operable measuring circuit will however increase the overall cost.